1. Field of the Invention
The present invention relates to a thin client system as well as to a thin client terminal, a thin client server device, and the like suitably applicable to the thin client system, and in particular, to a system, a terminal, a server device, a method, and the like in which a thin client terminal applied to a thin client system is also available as, for example, a TeleVision (TV) phone terminal and a TV conference terminal.
2. Description of the Related Art
Thanks to reduction in the price of personal computers (PC) and network apparatuses today, most enterprises and firms attempt to efficiently achieve business and jobs by distributing terminals such as personal computers to most of the employees. As a result of the reduction in the PC price and the increase in the chance to use the personal computers, the maintenance job of the manager of the computers and the like in the firm also increases in proportion to the increase in the number of personal computers. The maintenance job includes, for example, update of the versions of operating systems (OS) and job application (AP) programs, fixing of bugs or debugging of the operating systems and the application programs, taking of countermeasures against hardware failure, introducing of anti-virus measurements, and extermination of viruses. Therefore, the operation management cost including the cost for the maintenance conspicuously soars, leading to a problem which cannot be ignored. The management cost increases tremendously in proportion to the increase in the number of employees.
As a method to reduce the management cost, there exists a system operation method called “server-based computing”. This is a system in which, for example, the personal computers (clients) used by the employees are assigned with necessary and minimum functions such that the resources such as applications (programs) and files (including data) are managed on the server side in a centralized fashion and the programs and data are accessed from the PC terminals through remote control operation.
In more detail, to achieve a job using a PC terminal, the operator activates an application program on the server side by use of devices such as a keyboard and a mouse on the PC terminal side. Screen data to be displayed on the PC terminal side is created by the application and then the screen data is transmitted to the PC terminal side through the remote control communication path. In the system configuration, data cannot be saved on the terminal side. The Internet Protocol (IP) network coupling the terminal with the server is used to transfer therethrough data of the keyboard (key stroke) and/or a mouse (mouse click) from the PC terminal and screen data (screen transition) of applications from the server. The screen data is transmitted by the remote control as below. According to a method in which the screen data is sent from the server side via the network to the PC terminal side to be displayed on the PC terminal side, the server side detects an update area or section of the screen and then compresses the updated screen data to transfer the updated screen data to the PC terminal side. The PC terminal side receives the data and sets the data as screen information to thereby update the screen. In this method, only the update section of information, i.e., the differential information is transferred, and hence it is possible to reduce the amount of data to be transferred through the network.
As above, by allowing the PC terminal to save therein only the remote control program, i.e., by preventing the PC terminal from storing the application programs and data other than the remoter control program, the thin client (TC) terminal not including the storage such as a hard disk device can be used as a terminal of the server-based computing system. After the enforcement of the Act for Protection of Personal Information, the TC terminal has attracted attention as a terminal that does not leak personal information. The use of the server-based computing system in which the TC terminals is widely spreading today.
For example, a server-based computing system employing thin client terminals has been described as a system to cope with information leakage in pages 50 to 53 of “Nikkei Communication, 25 Nov. 2005”. This article describes aspects of the system such as a system of network boot type and a system of blade PC type in addition to a system of screen transfer-type of the prior art.